Omnipolar EGMs accurately correlate with the regional left atrial wall thickness

Identifying tissue characteristics and standardizing substrate mapping in patients with atrial fibrillation (AF) is critical for improving ablation outcomes. Current evidence suggests left atrial (LA) wall thickness playing a role in arrhythmogenic substrate, yet the direct correlation between LA wall thickness and underlying voltage remains underexplored. A standardized voltage measurement with omnipolar technology may better depict the tissue characteristics and help guide treatment strategies.

We sought to determine whether a correlation exists between LA wall thickness (LAWT) and omnipolar voltage amplitude. Our hypothesis is that thicker regions of the LA wall will show higher voltage, suggesting a potential link between structural integrity and conduction properties.

The study included ten prospective and consecutive patients undergoing AF ablation with EnsiteX between 2023 and 2024. For each patient, LA wall thickness was automatically measured from 3D-segmented CT images using ADAS3D, and peak-to-peak omnipolar voltage (OT-EGM) values were obtained from high-density electro-anatomical maps. Analysis was performed for areas of the LA body. Anatomical and EAM data were merged and a correlation coefficient was calculated between OT-EGM and LAWT.

In stable rhythms (sinus rhythm and pacing), we observed a positive correlation (Spearman’s rho = 0.26, 95% CI: 0.22–0.29 in sinus rhythm; rho = 0.27, 95% CI: 0.24–0.30 in pacing), supporting our initial hypothesis. Conversely, in non-stable rhythms (atrial fibrillation and flutter), the correlation was weaker and inconsistent, with an overall negative trend in flutter cases (rho = -0.22, 95% CI: -0.26 to -0.18) and a modest positive correlation in atrial fibrillation (rho = 0.17, 95% CI: 0.13–0.21).

OT-EGMs show a positive and consistent correlation with LAWT during stable rhythms. As such, substrate based strategies should preferentially use stable rhythms to assess the substrate and tailor the ablation to the LAWT. Non-stable rhythms show altered conduction dynamics possibly due to electrophysiological factors impacting voltage assessment and do not reflect the underlying tissue characteristics accurately.

Thicker wall thickness - higher voltage